Method of and means for cooling compressors



Jul 12 1927.

y s. s. AIKMAN METHOD 0F AND MEANS FOR COOLING COMPRESSORS Filed Nov. 9, 1925 Patented July 12, 1927.

UNITEDQSTATES AND ELECTRIC COPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION 'OF WIS-` CONBIN.

1,635,524! P A'isN'r oFFicE., f

BURTON B. AIKHAN, OF MILWAUKEE, WISCONSIN, ABSIGNOB T NATIONAL BRAKE METHOD OF AND MEANS FOBCOOLING COHPBESB-OBS.

Application led November 9, 1925; Serial No. 67,724.

This invention relates to, an improved method of and means for :cooling compressors and the like.

In the operation of tluid compressors and the like, cooling means are provided for preventing excessive tem ratures 'which would otherwise impairV lu rication and result in injury. Y

The water jacketing of a compressor now l0l in common use is not entirely satisfactory.

The heat that may be transmitted throughl dial depth of the water jacket, it is impossible to transfer much heat to the liquid passing through the jacket. As a result, either a large circulation or a large water consumption are required.

Furthermore, as pointed out in my copending application, Serial No. 737,725, tiled September 15, 1924, in certain coinpressors the cylinder head cannot readily be cooled in this manner.

It is the object of my present invention to p/rovide an improved method of and means for cooling that will better serve the purpose for which a cooling system is intended,

particularly for the cooling of compressors with relatively high rotative speeds of crank shaft, than can be accomplished where the conventional method of cooling by the conductance of the heat through the walls of; the compression chamber is employed.

l According to my present invention, I provide means for increasing the efciency of the cooling system b subjectin the working iid .directly to the cooling iquid which may be water or any other liquid or medium lfound suitable or preferable for the purpose. /This direct heat transfer permits maximum 5o equalization of the temperatures of the working and cooling fluids so that a higher volumetric eiiiciency of the cooling system may be secured.

In my system of cooling, the cooling liquid receives heat .from the compressed gas not only to raise its temperature t .that of the compressed gas (heat of the liquid), but

the cooling liquid also receives suflicient heat from the compressed gas to vaporize the 4 presence of the cooling medium, the workv ing pressures of the compressor is utilized to raise the boiling point of the coolin liquid with a still further increase in the e ciency thereof.

I .also rovide means for controlling the cooling uid supply to the compressor bv the temperature of the compressed flui This controlling means may be re lated or adjusted so that no water or cooling liquid will enter thecompression chamber until the temperature rise durin the compression stroke is sufficiently hig to completel evaporate that water that-is entrained wit the air during the intake stroke. My experiments show that this temperature is approximately 150 C."

I further provide means for deliverin and mixin the cooling liquid with the air entering t e compressor and means for shutting oil' the cooling liquid supply at thel desired part of the c cle'of operation of the compressor, regardless of the condition of tlie thermostatic control means.

In a compressor of the type employin a sleeve valve moved by my friction as 'sclosed in my aforesaid invention, it is difficult to employ water jacket cooling for the cylinder or sleeve walls and my present invention is peculiarly adapted to the cooling of such a' compressor. However, it is also applicable to an other form of compressor.

To acquaint those skilled in the art with the manner rof constructin andy practicing the invention, I-shall now escribe the same in connection With a specific air compressor embodying the invention.`

In the drawings, the single figure shows in vertical section a compressor embodying the features and involving the method of the present invention.

In the particular embodiment of the invention shown in the drawings, the com pressor is of the type disclosed 1n my coending applications, Serial No. 737,725, Eled September 15, 1924, and Ser1al No. 54,632, filed September 5, 1925.

The base 5 supports the crank case structure 6, The upper section 7 of the crank case structure merges into a cylinder heus# ing 8 having the upper and lower internal annular or cylinderical bearing surfaces 9 and 10 for the sleeve or liner 12 which controls the admission into the cylinder and acts also as a cylinder for the piston 13.

. The piston 13 is connected by a connecting rod 14 with the crank shaft 15 suitably journaled in the crank case structure The cylinder housing 8 has a cylinder head 16 which niay be secured as by means of cap screws 17 over the upper open end or top thereof. The head 16 contains a suitable seating ring 18 preferably' of y1elding resilient material. The ring 18 may be mounted in an annular pocket or recess in the head 16 and it' is positioned t6 engage with the annular inturned flange 19 at the upper end of the sleeve or liner 12 to make a fluid tight joint and for noiseless sealing engagement with the upper end ofthe sleeve or liner 12, which is reciprocated between, the limits of its movement by the frictional engagement of the piston 13 therewith. p The cylinder head 16 has a discharge opening 20 which has a valve seat controlled or adapted to be closed by a discharge check valve 22. The discharge valve 22 comprises, in this case, a ilat disc disposed within the discharge chamber 25 and held to its seat by a coiled sprin 26 interposed between the valve 22 and t e inner end of the out-v let or discharge fitting or lug 28. The discharge chamber 25 may e formed in the cup-like shell or cylindrical discharge housing 30 and communicates with the c linder or compression chamber through t e dis-l charge passageway 20 when the valve 22 is g unseated. T he shell or housing 30 may be formed integral with the cylinder head 16 L. at its lower end and its upper end may be internally threaded at 32 to receive the fitting plug 28 which may have an internally threaded socket 29.

Below its upper end the sleeve or liner 12 has an external or annular flange or shoulder 35 which is adapted to contact or abut with a yielding stop seat o r ring 36 for silently stopping the downward movement of the liner 12. The seat or ring 36 is preferably of yielding material and may be made of the same material as the seating ring 18.

The compressor piston 13 has suitable rings 40 for maintaining a fluid tight fit between the piston and the walls of the sleeve or liner 12. The piston may have inclined oil passageways 102 leading through the piston from the external surface thereof below the piston rings back to the crank oase.

The upper end-of the liner 12 is surrounded by an annular intake conduit or chest 42 formed in the upper end of the cylinder -housf ing 8. The cylinder housing 8 also has a lateral intake passageway 45 opening into the annular intake conduit 42.

The valve housing is secured as by means of cap screws 47 to the side of the cylinder housing 8 over the passageway 45 with its passagewayv48 in communication with or opening into the passageway 45. The housing 50 comprises the part or section in which a passageway 48 is formed and this part may have4 an externally threaded hub portion 52 to receive the other valve housing part 53 and an annular seat 54 concentrically surrounding the same.

The valve housing 50 has an inlet chamber 56 and the air or other working fluid is admitted through lateral inlet openings 58 and an axialinlet passage -to the chamber 56 from which it is drawn orpasses through the passageways 48, 45 and conduit 42 into the cylinder or in the charging cycle of thecom- While I have embodied my invention as disclosed in an air compressor, it is to be understood that the invention may be employed in compressing other compressible fluids and in fact wherever else found suitable or desirable. Also, while I find water particularly suitable-as the coolin'g fluid and shall describe the invention in connection therewith, it is to be understoody that other coolin fluids ma be employed in securing parta y or comp etely the improvements of the vpresent invention. Therefore, where I speak of an air compressor or air and a cooling liquid or water, I intend to cover generally a fluid compressor and any suitable cooling liquid or medium.

The axial inlet passageY 59 has a seat 60 controlled or adaptedto be closed by a combined water cut-ofi' and mixing valve 62. The valve 62 is preferably of conical formation as shown and has a hollow stem 63 guided in a guide 64 held centrally or axially 1n the passageway 59 by a web or spider formation 65 which properly positions the guide 64 and, at the same time, permits the working fluid and coolin mixture to pass around the guide through t e passageway 59 to the compressor. The valve 62 is held to its seat by a coiled spring interposed between it and the guide 64 or the web or spider formation 65, as shown. The valve housing part 53 has an annular seat and an air strainer 67 which may be of suitable screen or mesh formation surrounds and forms an annular intake to the valve housing 50, to prevent the entry of foreign matter into the compressor.

The part or head 53 of the valve housing has an axial depending water or cooling e or cooling iiui fluid nozzle or (jet 68 provided with a water inlet assageway 70 which l eads from a chamber 2 formed in the hub or valve stem housing 63 which may be integral with the part 53. The water linlet passageway opens at'its inner end into the chamber 72 and ma be rovided at its outer end with a threade soc et 76 to receive the water su ply pipe 77, which may lead from any suita le source, as for example, the city water mains or a tank or pump.

The upper end of the passage 70 may be controlled by a water controlling valve 78 which may have a tapered end to seat upon a cooperatin seat 79. The valve stem 78 extends throug 1 the valve stem housin 73 and the valve stem assage may be seale against the outward lea age of water or cooling iuidH by suitable packing 80 and gland means 82.

At its outer or upper end the valve stem 78 has pivotal connection at 83witha bell crank arm 84 which has fixed pivotal sup port at 85 upon a bracket which may formed integral with the housing part 53.

For the purpose of automatically controlling the quantity of water that may enter the compression chamber during the charging c cle or intake stroke by the temperature of the dischargin compressed air, I rovide a thermostatic'e ement which may e in the form of a cylindrical rod 86 formed of suitable material such as brass, copper or the like, the expansion or contraction of which with respect to the viron casing 87, will properly control the 'water control valve 78 1n accordance with the desired cooling demands of the compressor. l

The thermostatic rod 86 is enclosed in a housin or container 87 preferably of cast iron, w ich forms a part of the lair discharge line from the compressor. The housing 87 has a hollow nipple 88 which may be threaded into the socket 29 of the air discharge plug 28, placing the internal chamber 89 of 4the housing 87 in communication withthe air discharge from the com-A pressor. The opposite side of the housing 87 may have a threaded socket to receive the' air discharge pipe 90 which leads to'the air storage reservoir or any otherv desired point.

The thermostatic rod 86 is seated and pinned at one end in a plug member 92 which may be threaded into one end of the hous.- ing 87, thereby closing off that end of the housing. The end of therod 86 is fixed in the plug 92 by a pin 93. The opposite end of the rod 86 extends and is s lidable through the opposite end of. the container 87 and is free to act upon the arm 94 of the bell crank arm, the passage of the rod 86 through the end of the housmg 87 being preferably sealed against fluid lea age by suitable packin 95 and gland means 96.

he projecting or actuating end of the rod 86 may be rovided with Aan adjustment, so that it may e adjusted to lift the water or cooling fluid control `valve 78 from its seat when any desired temperature. of the 89. This adjustingcmeans ma head 97 threaded upon the ro tact with the bell crank arm 94 and held] firmly in place by a lock nut 98. When the thermostatic element 86 is contracted suiiiciently to permit same', the water control valye .78 is held to its seat by a coiled sprlng 99.

The compressed air and watervapor passes onto the air receiver not' shown where the temperature of the same is lowered by contact with the atmospheric air. be used. Here the water condenses out and may be removed by hand or automatically as dy a suitable trap and, if desired, again use discharging fluid is reached in the chamberl comprise a l 86 for con- A cooler may f While the above construction is shown embodied in a simple single cylinder acting type compressor with control means tor mamtamlng a predetermined temperature inthe discharge fpassageways of the com-.

vided with a dome or stud 100 for entering the discharge passageway 20 and assuring 'substantially com lete discharge of the compressed fluid, t e dome or stud 100 during the downward movement of the pistonl actingas a suction plunger in the passageway 20. A relatively small port or drill hole is provided at the bottom of the mixing valve chamber to safeguard against iooding the compressor by leakage that might exist at the water valve openings due to defective seatin or the like. y

The particular mlxing valve which I have lOl] shown might be replaced b a suitable carn buretor using water instea of hydrocarbon fuel, or any other suitable liquid and gas contact apparatus which can be brought under suitable thermostatic control by the temperature of the compressed air.

.The operation of the embodiment shown" is as follows Y Assuming that the discharge air line and the water connection be suitably connected to their respective parts, upon starting the compressor the initlal downward movement of the piston 13 moves the liner 12 with it by the ring friction therebetween, until the flange 35 strikes the yielding sto 'vor seat 36. As the upper flanged endo the liner moves awayv from the'yielding seat 18,

the combined water cut-off and mixing valve will promptly open, but the thermostate element being in contracted condition, the

Athermo-controlled water valve'willremain in closed osition and no water -wi1l lbe admitted or cooling purposes.

There is preferably no water yadmission kto the compression chamber until the temperature of the compressed air is sutliciently high to completely evaporate the water that is entrained by the air during the intake stroke. This temperature has been found to be ap roximately 150 delgi-ees centigrade for sing e stage compression. Therefore, upon starting the compressor and until the temperature of the compressor rises to s uch a point that the discharging 'fluid 1s raised sulticiently to operate the automatic thermocontrol, the water remains shut olf even though valve 62 is opened.

While the thermostatic rod 86 is responsiye to the temperature of the compressed air discharged by the compressor, it 1s to be understood that the rise in temperature of the air for an adiabatic compression of from normal rooin temperature and pressure to discharge )rassure of the order of 100# per square inch is not suii'cient to cause operation of the thermostatic rod. The cylinder Walls and head are conductive and take heat from the air under compression to a greater extent t-han they give it oil'. In turn, they heat the incoming air and further increase' its temperature. The result is a cumulative elfect which builds up the temperature on continuous operation to a temperature which, 1f not prevented, will be suliicient to destroy lubrication and to destroy the valve seat 18. Hence, the thermostatic element, although it is directly affected by the compressed airl temperature, is actually responsive coinpressor temperature. The air in this case serves merely as a connecting medium between the compressor'itself and the thermostat. The thermostat might be in direct conductive relation to the walls or head of 4,the compressor, but practically this would be difficult to accomplish.

As the temperature of the discharging fluid increases due to heating of the compressor suliiciently to expand the thermostatic element 86 longitudinaly, the expansion of said element will, by its contact with the bell crank arm 84 swing said arm in a direction to lift the valve stem 78 from its `seat 7 9, thereby opening the water or cooling fluid inlet to the valvevand mixing chamber housing and through 'same to the compression chamber. The admitted water is graduated` by the thermo-controlled water valve so that it is a function of the expansion and contraction of the rod 86 and the expansion and contraction of that rod being a function of thechange in temperature of the dischargin air and that in 'turn being a function o the temperature of the compressor, the water admission may be made a function of the compressor temperature, so

`passes from the line 77 past the valve 62 with the incoming air when said valve 62 .is

'opened during the suction cycle ofthe compressor. The conical sha e of the valve body 62 breaks up the water y the action of the air in its passage across the lower edge of the valve skirt, tending to atomize and to thoroughly mix the Water and air which then pass from the mixing chamber into the compression chamber or cylinder of thecompressor. y

By admitting the cooling liquid intothe compression chamber with the working fluid, the working fluid and the compressor walls are subjected directly to the cooling liquid for the direct transfer of heat instead of through jacket walls or the like. This materially increases the volumetric eliiciency of the cooling medium in its cooling function.

Upon a fall in the temperature of the discharging air in contact with the thermal 'or thermostatic element indicating cooler cylinder walls, the thermal controlled water valve is adapted to close and remain closed until the air temperature again reaches a point Where it will open. Upon stopping the compressor, the combined Water cut-olf and control valve 62 promptly closes under the action of the coiled spring for seating the same and shuts olfor closes the air intake. is purely incidental. At the Sametime, the upper end of the valve 62 seats in the lower end of the water nozzle 68 and closes olf the cooling water supply. This is the desired function. This closes the watersupply against' leakage where 'the compressor 1s stopped with the valve 7 8 unseated or open under the, action of the thermal element, and the thermal element controls the valve 78 independently of the action of the valve 62.

From the foregoing it will now be apparent that I have provided a cooling system and method of increased efliciency, a system and method better adapted to serve the purpose for which intended, and that the quantity Vof Water consumed for cooling purposes is greatly decreased. This eliminatesV This the necessity of maintaining a large supply vhaving an inlet for gas, means for deliversaid intake passageway upon the suction stroke only of the compressor.

2. In a compressor having an intake valve an intake passageway leading thereto, an Water spray means actuated 'only during the suction stroke to discharge theliquid into the gas flowing through said intake passage- ?.T In combination, a compression chamber having an inlet valve and an inlet for the working fluid, means for delivering a cooling fiuid to said inlet, and a suction operated valve in said inlet for controlling the working and cooling fluid supplies.

4. In combination, a compression chamber ing a cooling iuid to said inlet, a valve in sald inlet for controlling the gas and cooling fluid supplies, said valve being formed to mix the gas and coolin uid in their passage to the compression c amber.

5.'In combination, a` vertical cylinder housing having a movable liner, a piston operable in said liner, said housing having a conduit surrounding the top of the liner and being disposed partly below the top of the liner, a working fluid inlet opening into said conduit, means for delivering a cooling liquid to said working fluid inlet and a combination working and cooling uid cut-olf and mixing valve in said inlet.

6. In a compressor, a compressor c linde'r, an intake valve, a suction pipe t erefor, and a suction operated water atomizing device discharging into said suction pipe only when a current ,of gas is flowing therethrough in response to suction.

7. In combination with a compressor having a iston and a cylinder, an inlet passageway or the c linder, and a water mixing valve .opened y the piston on its suction stroke to discharge water into the stream of gas drawn into the inlet gas passageway.

8. In combination with a compressor having a piston and a cylinder, an inlet gas assageway for the cylinder, andda movable arrier in the inlet passageway, means for spraying water into the air passing said barrier, and a valve operated byA said barrier for controllin said means.

9. In comination with a compressor having a piston. and a cylinder, an inlet as passageway for the cylinder and a mova le arrier in the inlet passageway, means for spraying water into the air passin said barrier, a valve operated by said barrier for controlling said means, a discharge gas passageway for the cylinder, and a thermostatic element subject to the temperature of the gas in the discharge passageway for controlling the water delivered by said means.

10. In combination with the intake passageway of a compressor, a. mixing valve comprising a passageway communicating with a source of cooling liquid, a movable valve member normally closing said cooling liquid passageway and the air inlet passageway, and spring means for holding said valve in closed position.

11. In combination with the intake passageway of a gas compressor, an intake valve controlling said passageway, a source of Water, a suction operated metering device for injecting water from said source into the current of gas drawn by the compressor through the intake passageway, and means for separating outany water not in suspension in sai intake passageway.

12. The method of cooling a gas compressor which comprises moving the piston outwardly in the cylinder to create a drop in pressure in the cylinder and intake passageway of the compressor, causing a flow of air into the cylinder by said drop in pressure, injecting cooling liquid into the flowing current of air in accordance with the drop in pressure, and carrying the cooling liquid in suspenslon in the current of air into the cylinder.

13. In combination, a compressor having a cylinder, .a lateral air inta e passageway into the cylinder, an atomizer casing supported on said cylinder and having a passageway communicating with said intake passageway, a sprin loaded valve in said casing normally closing off the passageway to the casing, said casing having a liquid passageway terminating in a dischar e port also controlled by said spring loade valve, a needle valve for said liquid assageway for controlling the rate of liquid elivered to the discharge port, said cylinder having a discharge passageway, a thermostat housing communicating with said dischargepassageway and mounted on said cylinder, 'a thermostatic rod in said housing subject to the temperature of the gas discharged from the compressor and connected to said needle valve.

In witness whereof, I hereunto subscribe my name this 6th dav of November, 1925.

. BURTON S. AIKMAN. 

